Enhancement of content, purity and anti-myocardial ischemia–reperfusion injury activity of persimmon leaf flavonoids: Ultrasonic-assisted extraction, purification and related mechanism

Persimmon leaves (PL) are agricultural and forestry by-products rich in flavonoids with diverse pharmacological activities. To fully exploit their medicinal value, we established an optimized integrated process combining ultrasound-assisted extraction (UAE) and resin purification to efficiently prepare persimmon leaf flavonoids (PLF) with high content and purity. The chemical composition of PLF was comprehensively characterized by ultra performance liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) and high performance liquid chromatography (HPLC). Furthermore, in vitro cell and in vivo rat models were employed to evaluate the activity and underlying mechanism of PLF against MIRI. Preliminary results showed that the content and purity of PLF prepared by the proposed process were significantly higher than those of crude PLF (C-PLF) obtained by conventional reflux extraction. The total flavonoid content (TFC) and mass fraction of total flavonoids in PL (TFPL) were 48.54 ± 0.86 mg/g and 87.78 ± 1.61%, respectively. In addition, in vitro pharmacological revealed that PLF exhibited significantly stronger anti-oxidative stress activity than C-PLF. Four monomeric compounds, namely hyperoside, isoquercitrin, kaempferol-3-O-galactoside and astragalin, exerted synergistic effects. In vivo animal experiments demonstrated that PLF alleviated myocardial infarction and oxidative stress injury in MIRI rats, and exerted cardioprotective effects by regulating oxidation-related proteins. At present, there are few studies on high-quality PLF worldwide. This study not only verified the high efficiency of UAE in flavonoid preparation, but also proved that high-purity PLF possesses prominent advantages against MIRI. The results provide a theoretical basis for the comprehensive development and utilization of PL resources.